KDP book cover dimensions, explained

August 10, 2026 · 3 min read

Cover rejections on KDP are nearly always dimensional rather than aesthetic, and nearly always one of four things: the wrong aspect ratio on an ebook, a spine width calculated for the wrong page count, missing bleed, or text sitting too close to a trim edge.

Here is what each measurement is and where it comes from.

Ebook covers

An ebook cover is a single flat image — no spine, no back. The thing to get right is the aspect ratio: 1.6:1, height to width. A 1600 × 2560 pixel image hits it exactly and is the size most designers deliver.

Amazon asks for at least 1000 pixels on the longest side and will accept considerably larger. Go too small and the cover looks soft on a modern high-density screen; the wrong ratio and it gets letterboxed with bars, which reads as amateur at thumbnail size.

Paperback covers

A print cover is one continuous image covering back, spine and front, plus bleed. Four numbers go into it.

Trim size

The finished page size. 6 × 9 inches is the default for most fiction and general non-fiction; 5 × 8 and 5.5 × 8.5 are common for smaller-format novels and memoir. Pick this before anything else, because everything downstream depends on it.

Bleed

If any colour or image runs to the edge of the finished book, the artwork must extend past the trim line so that normal cutting variation does not leave a white sliver. KDP specifies 0.125 inches of bleed on the outer edges. Extend the background into it; put nothing there you need to keep.

Spine width

This is the one that depends on your book and the one people get wrong. Spine width is page count multiplied by a per-page thickness that varies by paper stock — white and cream paper differ, and colour stock differs again.

Two consequences follow. First, you cannot design the spine until the interior is final, because adding two pages changes it. Second, use KDP's own cover calculator rather than a general formula — it takes trim size, page count and paper type and returns a template sized for your exact book.

Amazon does not print spine text at all below a threshold of around 100 pages, because the spine is too narrow to hit reliably.

Safe margin

Keep text and logos at least 0.25 inches inside the trim line on every edge. Cutting varies by a small amount on every copy; a title set flush to the edge will be shaved on some of them. On the spine, keep text clear of the folds — spine text that is perfectly centred in the file can still drift onto the front or back cover in printing.

File format

• Print covers: PDF, with fonts embedded and images at 300 DPI. Flatten transparency before export.
• Ebook covers: JPEG or TIFF, RGB, sized to the 1.6:1 ratio.
• Print is CMYK. Colours that glow on screen — bright blues, deep reds — print duller. This is normal and is the single most common surprise on a first proof.

The order that avoids rework

1. Choose the trim size.
2. Finish and format the interior, and get the final page count.
3. Download the cover template for that exact trim size, page count and paper type.
4. Design onto the template.
5. Order a printed proof and look at it under daylight before approving.

Designing the cover before the interior is final is the usual cause of the second and third versions of a cover file. The spine is the reason.